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Which way it blows, and how far you see

ยท 2 min read
Massimo Di Stefano
FastGIS author

Two more answers on the weather timeline, closing the hazards set that started this morning with snow and thunder: the gust layer now says from where it blows, and a fourth layer says how far you can see.

Arrows on the gustsโ€‹

A 60 km/h gust is survivable as a headwind and frightening from the side. The gust layer draws a lattice of small arrows over its colours, pointing where the wind blows and growing with the gust; on the calm parts of the map, where the colours fade out below 30 km/h, a short grey barb still gives the direction. The plan sheet carries the same arrow after each stop's gust value โ€” ๐Ÿ’จ 31 km/h โ†—.

The direction comes from the forecast model's wind components across Europe and from MET Norway's 1 km forecast in the Nordics, inside the same frames the layer already draws; directions are combined as vectors, never averaged as angles, so a wind from just west of north never comes out as "from the south".

A visibility layerโ€‹

Pick ๐ŸŒซ on the bar and the map shows fog and haze โ€” and nothing else. The layer is grey where visibility drops under 5 km and darkens towards 200 m; clear air is not drawn at all, so an empty map means you can see. In the Nordics it comes from MET Norway's MEPS 2.5 km model, which also knows where its cells are foggy; across the rest of Europe from ICON-EU. Fog also marks the rain layer and the stop captions with ๐ŸŒซ, and a stop's line mentions visibility only when it is under 5 km (๐ŸŒซ 0.8 km) โ€” a clear morning does not need a number.

Same frames, same manifests, same tile URLs as before: an older build of the app simply does not see the new band and the new layer.